concat$

Appends arrays to the end.

array.concat$(x, ...ys);
// x:  an array (updated)
// ys: arrays to append
// --> x

const array = require('extra-array');

var x = [1, 2];
array.concat$(x, [3,  4]);
// [1, 2, 3, 4]

x;
// [1, 2, 3, 4]

var y = [5, 6];
array.concat$(x, y, y);
// [
//   1, 2, 3, 4,
//   5, 6, 5, 6
// ]

references

• Array.prototype.concat(): MDN web docs